Lock-up in server screen

Have anyone encountered problem when entering screen ans BF freezes?
I have to now shut down network connection, then choose favourite server and then put connection ON.
Or I use +joinserver...straight
I havent change anything on my system, disabled and uninstalled PB, disabled firewall and MSSE.
I use Xp Pro and 4G mobilephone on USB or wifi tethering.
Havent changed anything, worked a week a go just fine ???